According to a report issued October 2003 by Statistics Korea, 7.2% of the total population of South Korea was 65 or older in 2000, indicating the entry of the country into the category of an aging society. By 2019, Korean society is expected to become an aged society as the elderly population will reach 14% or higher. With the rise of aging problems as a social issue, nationwide attention has intensively been paid to elderly welfare such as characteristics, living, health, culture, and leisure of the elderly population, together with an increasing demand for statistical data on welfare. One of the most important problems occurring with an increase in the elderly population is chronic degenerative diseases. This is in contrast to acute infectious diseases, which have been the main cause of death over the past five decades. Of chronic degenerative diseases, cerebrovascular diseases are observed to rank second among all mortality attributed to individual diseases.
Cerebrovascular diseases are largely divided into two types: hemorrhagic cerebral diseases, such as cerebral hemorrhage, and ischemic cerebral diseases, such as that caused by cerebrovascular occlusion. While traffic accidents account for many cases of hemorrhagic cerebral diseases, ischemic cerebral diseases is frequently observed in the elderly.
Transient cerebral ischemia, if introduced, blocks the supply of oxygen and glucose to the cerebrum, with the subsequent decrease of ATP levels and the generation of edema in neural cells, resulting in damage over a wide region of the brain. Death of neural cells is observed when a significant period of time is passed after the occurrence of cerebral ischemia, and thus is called delayed neuronal death. An experiment conducted on a transient forebrain ischemic model using Mongolian gerbils reported that neuronal death occurs in the CA1 region of the hippocampus four days after the introduction of cerebral ischemia for 5 min (Kirino T, Sano K. Acta Neuropathol., 62: 201-208, 1984; Kirino T. Brain Res., 239: 57-69, 1982).
Thus far, two mechanisms of cerebral ischemia-induced neuronal death are known: one is the excitotoxic neuronal death mechanism, in which excessive glutamate accumulates outside cells upon cerebral ischemia, and flows into cells, with the concomitant intracellular accumulation of calcium, thereby inducing neuronal death (Kang T C, et al., J. Neurocytol., 30: 945-955, 2001); and the other is oxidative neuronal death, in which abrupt oxygen supply upon ischemia-reperfusion increases free radical levels to give rise to the injury of the DNA and cytoplasm (Won M H, et al, Brain Res., 836: 70-78, 1999; Sun A Y., Chen Y M., J. Biomed. Sci., 5: 401-414, 1998; Flowers F, Zimmerman J J, New Horiz, 6: 169-180, 1998).
On the basis of the disclosed mechanisms of ischemia-induced neuronal death, much research has been directed toward materials that can inhibit ischemia-induced neuronal death, together with their functional mechanisms. However, almost no materials that inhibit cerebral ischemia-induced neutral death effectively have yet been found.
Tissue plasminogen activator, which is a commercially available cerebral ischemia treating agent solely approved by the FDA, is thrombolytic agent that break down the blood clots to induce for the rapid supply of oxygen and glucose to the brain. However, tissue plasminogen activator must be used immediately, as it does not directly protect nerve cells. Moreover, the thrombolytic function has the risk of causing hemorrhagic cerebral diseases when the agent is used frequently or in excessive doses.
MK-801, a calcium channel blocker for effectively inhibiting early-stage calcium ion influx, was abandoned as it was found to have adverse effects during clinical trials thereof.
Meanwhile, in South Korea, many health care foods containing natural substances are on the market and are promoted as being preventive of stroke. However, most such products have not yet been scientifically verified, and are frequently abused, causing various social problems.
There is therefore an urgent need for the development of a natural substance that is scientifically proven for therapeutic or preventive effects on cerebral diseases.
Sceptridium ternatum is a perennial grass taxonomically classified in the Ophioglossaceae family of the Ophioglossoides order in Pteridophyta. In South Korea, the plant grows naturally in high mountains in Jeju Island, Jiri Mountain, Deogyu Mountain, Kyeongnam province, Kyeongbuk province, Kangwon province, and Kyeonggi province, and is frequently found in semi-shaded grasslands in fertile soil and humid environments.
Nowhere has research into the neuroprotective effect of Sceptridium ternatum extracts on brain nerve cells, particularly in animal models, been reported.